A Field Study of Biosolids Sampling Practices to Meet 503 Requirements

The overall objective of this WERF project (04-HHE-7) was to develop strategies to obtain representative samples for each liquid, cake and compost biosolids products. The work reported on in this paper involved a field study of nine POTWs across the country. The field study was designed to test the best biosolids sampling approaches and assess the value of the approaches in use at POTWs to meet Part 503 requirements. Three sites each producing liquid, cake, and composted biosolids were selected. The sites represented a cross section of facility sizes. Facility staff interviews identified their strategies, techniques and schedules for biosolids sample collection and testing. Historical data was reviewed for variability among the testing results. In comparison, seven discrete 1L samples were collected and analyzed for fecal coliforms (using EPA-approved Method 1680) from each site to assess single batch variability. The information and results were evaluated to develop recommendations for best practices.